Forde has a year left on his contract and is a reported target for Premier League side Hull following a fine season for the Lions.
But new Den chief Lomas hopes to persuade the 33-year-old, a former team-mate from their days at West Ham, to stay put in south London.
He said: "I know Fordey from when he was a young kid at West Ham and all credit to him. He didn't get an opportunity so he went back to Ireland, he had the right mentality and then came back with Cardiff.
"He's built himself up to be Ireland's number one now, he had a great season last year and obviously you want to keep your best players.
"David has a year left and we'd certainly like to keep him for the foreseeable future. But there are a few players with a year left and that's a challenge for me, to sit down and prove to them that Millwall are going in the right direction.
"It certainly would have to be a hell of a bid for us to even contemplate getting rid of David Forde."
Lomas says he has yet to decide on the make-up of his backroom staff.
Lions legend Neil Harris, currently playing for Southend, has been linked with a return to the club where he is record goalscorer in a coaching role.
But Lomas, who replaced Kenny Jackett in the Den hotseat, will hold talks with current coaches Joe Gallen and Tim Breacker before making any decisions.
"Kenny has left Joe and Tim, both of whom I know well, so at some stage we will sit down, have a chat and see what their plans are. I don't think it will be a problem," said Lomas.
"I've had it happen to me at other clubs where, through no fault of your own, you end up getting released and I don't think that's the right thing.
"We'll have a chat with the people here and see where it takes us and see if they want to stay at Millwall."